For the next two weeks before the May 18 primary, Muhlenberg College/Morning Call will be releasing daily horse race polls from a telephone survey of likely Democratic voters. The sample size will be about 400 Pennsylvanians and the margins of error will average around +/-5 percent at a 95 percent level of confidence.

The first poll, released Saturday night, shows Rep. Joe Sestak gaining on Sen. Arlen Specter. Specter had enjoyed double digit leads over Sestak, but Sestak has narrowed that lead to just 6 percentage points (48 percent to 42 percent).

This poll is the first since both candidates went up on television with commercials a few weeks ago.

Interestingly, despite Sestak gaining ground, Specter's favorability in this poll is higher than it had been in most other public opinion polls this campaign cycle. Of those surveyed, 51 percent had a positive view of Specter compared to the 31 percent who didn't. Only 10 percent were undecided about the 30-year incumbent senator.

Sestak's favorability is 45 percent with 44 percent undecided.

The two candidates debated Saturday night, which will likely be the final face-to-face matchup before the election. Read full coverage of the debate here.